Preheat the oven to 190ºC/170ºC fan and line three 20cm/8inch cake tins.
In a large bowl, beat together the unsalted butter and caster sugar until combined.
Then, add your eggs, whole milk, self raising flour and baking powder, and beat until combined again - but be careful to not over beat.
Divide the mixture equally between the three tins and smooth it over.
Bake for 25 minutes until the cake is golden and springs back (a skewer should also come out clean).
Turn the sponges out onto a cooling rack and leave to cool fully.
Beat the unsalted butter with an electric mixer until it's smooth and loose.
Then, gradually beat in the icing sugar & vanilla extract.
If the icing is too stiff, add 1 tbsp whole milk at a time to get your desired thickness!
Spread or pipe the buttercream onto the top of one of the sponges, then spoon on half of your jam.
Place the second sponge on top and repeat the process - finish with the third sponge, and any left over buttercream on top!
Add some fresh strawberries, perhaps a sprinkle of icing sugar and serve!
When decorating the cake, I like to pipe a small amount of the buttercream around the edge of the sponges, then put a little more in the middle with the jam on top - this stops it falling out all over the place, but this is simply my choice! :)
This cake will last in an airtight container for 3 days, or you can freeze it for up to 3 months!